THE EFFECT OF TEMPERATURE ON THE ELECTRICAL AND DIELECTRIC PROPERTIES OF MANGANESE FERRITE NANOPARTICLES

Abstract

In the present study, MnFe2O4 and Mn0.85Zn0.05Cu0.1Fe2O4 ferrites were successfully synthesized by solid state reaction method. The thermal, structural, electrical and dielectric properties of these ferrites were investigated using different characterization techniques. From thermogravimetric analysis (TGA) and differential thermal analysis (DTA) study, compound formation temperature as well as the weight loss regions was identified for both compounds. The X-ray diffraction (XRD) patterns of the synthesized samples confirmed the formation of spinel structure with Fd-3m space group without any secondary phases or impurity. The crystallite sizes for the two compounds were calculated from most intense peak (311) using the Scherer formula and they were found to be 70.8 nm and 61. 9 nm for MnFe2O4 and Mn0.85Zn0.05Cu0.1Fe2O4, are respectively. This confirmed the nanocrystalline nature of both synthesized materials. The lattice parameter, unite cell volume, x-ray density, bulk density, porosity, surface area of both synthesized ferrites were also calculated from the obtained XRD data. From FT-IR spectroscopy study, two strong metal-oxygen absorption bands, which are commonly observed in ferrite materials, were obtained at 585.5 cm–1 and 594.4 cm–1 in MnFe2O4 and Mn0.85Zn0.05Cu0.1Fe2O4 spinel ferrites, respectively. The cole-cole plot, complex impedance, dielectric permittivity and ac conductivity of Mn0.85Zn0.05Cu0.1Fe2O4 were measured at different temperatures in the variable frequency ranges of 20 to 1 MHZ. It was found that the values of the ac conductivity and dielectric permeability were increased with increasing temperature, which is an expected behavior of ferrites. This is a very important feature for power applications of ferrites. It was also observed that the real and imaginary part of impedance values were typically higher at lower frequency region for different measured temperatures and for increasing the frequency, the impedance decreased. The high value of impedance at low frequency region is due to the high polarization caused by space charges in samples. Both the dielectric constant and the ac conductivity of Mn0.85Zn0.05Cu0.1Fe2O4 increase with an increase in temperature for all ranges of frequencies.